This invention pertains to throttle body assemblies for use with internal combustion engines and is particularly concerned with a new and improved throttle body having a blade-mounted deflector and a mixing tube for improved atomization and distribution of fuel, particularly advantageous for use in conjunction with an electronic fuel metering system.
Electronic fuel metering systems offer important advantages and benefits over other types of fuel preparation systems for internal combustion engines. In an electronic fuel metering system the quantity of fuel to the engine is metered electronically in accordance with certain control parameters. An example of such an electronic fuel metering system is shown in U.S. Pat. No. 3,935,851, assigned to the same assignee as the present application. A particularly desirable way to introduce the fuel into the engine induction passage is by utilizing one or more fuel spray bars which spray fuel as distinct jets into the induction passage. An example of such fuel spray bars is shown in U.S. Pat. No. 4,132,204, also assigned to the same assignee as the present application. In this latter patent the throttle body assembly which is used with the disclosed spray bar system has rectangular shaped induction ports with a pair of counter-rotatable throttle blades disposed in each port. Fuel is sprayed centrally of each port toward the opening defined between the juxtaposed edges of the throttle blade pair.
There are certain advantages to throttle bodies which incorporate circular induction ports, as opposed to rectangular or other shaped ports. For one, a circular shaped port is generally easier to machine from a rough casting than is a rectangular shaped port. Also, the circular shape is akin to that used in conventional, commercially available carburetors, and hence allows use of more or less conventional butterfly-type throttle blades. Heretofore however, the use of circular port throttle bodies and butterfly type throttle blades in conjunction with an electronic fuel metering system has been considered impractical for the purpose of achieving compliance with mandated governmental regulations relating to vehicle exhaust emissions and fuel economy.
The present invention provides a solution which is capable of rendering the use of circular port throttle bodies compatible with an electronic fuel metering system toward achieving compliance with mandated regulations. Thus, the invention means that a fuel mangement system can incorporate the benefits of both of electronic fuel metering technology and more or less conventional carburetor manufacturing technology insofar as the latter relates to manufacturing of the circular ports and blades. The invention requires a minimal number of parts, is of economical manufacture and performs well.
According to one aspect of the invention, a deflector mounts on the downstream face of the throttle blade to act much like spoiler in generating turbulence. According to another aspect, a mixing tube downstream of the blade generates additional turbulence. These features, individually and collectively contribute to improved fuel preparation.
The foregoing features, advantages and benefits of the invention, along with additional ones, will be seen in the ensuing description and claims which are to be considered in conjunction with the accompanying drawings. The drawings disclose a preferred embodiment of the present invention according to the best mode presently contemplated in carrying out the invention.